Table 4.7 Updated Action and Limit Levels for Water Quality

Parameter (unit)	Water Depth	Action Level	Limit Level
Dissolved Oxygen (mg/L) (surface, middle, bottom)	Surface and Middle	*5.0*	*4.2* except 5 for FCZ
Dissolved Oxygen (mg/L) (surface, middle, bottom)	Bottom	*4.7*	*3.6*
Turbidity (NTU)	Depth average	*27.5* and 120% of upstream control station’s turbidity at the same tide of the same day	*47.0* and 130% of turbidity at the upstream control station at the same tide of same day
Suspended Solids (mg/L)	Depth average	*23.5* and 120% of upstream control station’s SS at the same tide of the same day	*34.4* and 130% of SS at the upstream control station at the same tide of same day and 10mg/L for WSD Seawater Intakes

Note:

(1) Depth-averaged is calculated by taking the arithmetic means of reading of all three depths

(2) For DO, non-compliance of the water quality limit occurs when monitoring result is lower that the limit.

(3) For SS & turbidity non-compliance of the water quality limits occur when monitoring result is higher than the limits.

(4) All the figures given in the table are used for reference only and the EPD may amend the figures whenever it is considered as necessary.

(5) The 1%-ile of baseline data for dissolved oxygen (surface and middle) and dissolved oxygen (bottom) are 4.2mg/L and 3.6mg/L respectively.